Re: [gpsd-dev] ✘INCOMPATIBLE API change -- add gnssid:svid

[Eric S. Raymond]

Gary E. Miller <address@hidden>:
> Yo All!
> 
> INCOMPATIBLE API CHANGE!  The JSON is upwardly compatible, but not the
> binary.
> 
> satellite_t got bigger.  It now has gnssid and svid fields for each
> sat.
> 
> The GREIS, NMEA 0183 and u-blox drivers fill in these new fields.
> 
> If valid, the new fields are included in the SKY JSON.  The client
> library decodes them too.
> 
> Why?  PRN has become a mess.  No two GPS encode multiple GNSS into
> the PRN the same way.  Just NMEA 0183 does it four different ways.
> 
> gpsd had the gnssid:svid data from GREIS, NMEA 0183 and NMEA, but
> was trying, and failing, to mash it consistently into the PRN field.
> 
> No way the user could tell which PRN belongs to which constellation.
> 
> cgps and xgps use the new fields to show the user which constellations
> different satellites belong to.
> 
> Now, at least with those three drivers, the user can trivially see
> which constellation a satelltie belongs to.
> 
> Please go test.

An incompatible API change will require a major version number bump.
Also, see this list in TODO:

** Things to do when we can break compatibility **

In gps_data_t make device subtype longer. 128 chars long sounds good.

In gps_data_t, save PPS precision; this will require creating a pps struct.

In gps_fix_t, maybe change time away from float to timespec?

Add MMSI sequence number fields to AIS type 7.

I tried to make these breaks as infrequent as possible; ditro builders
don't like them.  So if we're going to have one now let's clear that
queu - either implement these changes or downcheck them.
-- 
                <a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>

My work is funded by the Internet Civil Engineering Institute: https://icei.org
Please visit their site and donate: the civilization you save might be your own.

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